1. Field of the Invention
The present invention relates to a paper-supplying device installed in an image-forming apparatus, such as an electrophotographic copying machine or a printer, in particular to a paper-supplying device in which a paper-supplying portion is charged with a paper-housing vessel by moving the latter in the direction of the rotary axis of a shaft of a paper-supplying roller.
2. Description of the Prior Art
In such paper-supplying device, if the paper-supplying portion is charged with the paper-housing vessel by moving the latter in the direction of the rotary axis of the shaft of the paper-supplying roller, a disadvantage occurs in that papers housed in the paper-housing vessel one above another are brought into contact with end face portions of the paper-supplying roller and can be torn or shifted sideways within the vessel.
An arrangement for eliminating such disadvantage has been proposed in Japanese Utility Model Application Laid-Open No. Sho 63-21630, wherein, as shown in FIG. 13, a paper-supplying device comprises a paper-supplying roller shaft 72, a paper-supplying roller 73 rotatable integrally with paper-supplying roller shaft 72 and movable in the direction of the axis thereof, and a paper-supplying roller holding member 74 relatively rotatably mounted on paper-supplying roller 73 and extending therefrom to project into the path of a vessel 71 containing or housing therein paper sheets during the time when a paper-supplying portion is charged with the paper-housing vessel 71. Holding member 74 is engaged by vessel 71 and moves together with the vessel 71, thereby moving the roller 73 along the shaft 72 during the time when the paper-supplying portion is charged with the vessel 71. Pressing force-applying means 75 applies pressing force pressing the paper within the vessel 71 against the roller 73 after the engagement of the vessel 71 with the holding member 74.
With such the construction, when the paper-supplying portion is charged with the vessel 71, the paper within the vessel 71 is separated from the roller 73 before the engagement of the vessel 71 with the holding member 74. However, upon charging the paper-supplying portion with the vessel 71, the vessel 71 is moved integrally with the roller 73 and the paper within the vessel 71 is pressed against the roller 73 by means of the pressing force-applying means 75, after the engagement of the vessel 71 with the holding member 74 (refer to FIG. 14) and, thus the paper effectively can be prevented from being torn and shifted sideways.
However, various sizes, for example calling card size to A0 size in JIS, of paper may be housed in the vessel 71 one above another, and thus the weight of the papers housed in the vessel 71 greatly varies. On the other hand, the force of means 75 pressing the paper against the roller 73 is constant, so that a disadvantage has occurred in that the actual force with which the paper is pressed against the roller 73 is greatly varied, depending on the size of the paper to be supplied. Therefore, the paper-supplying capacity for certain sizes of paper is remarkably reduced.
In addition, in for example an electrophotographic copying machine provided with the above described paper-supplying device in which the paper-supplying portion is charged with the paper-housing vessel by moving the latter in the direction of the rotary axis of the shaft of the paper-supplying roller, in the event that there occurs a shift of the optical axis between the manuscript and the paper on which images from the manuscript are to be copied, (a positional shift between the manuscript and the paper in a direction meeting at a right angle with the paper-supplying direction, more strictly the positional shift between the image-forming portion and the manuscript or the paper in the direction of the width of the latter), the manuscript-placing standard plate provided at an end portion of a contact glass is shifted in the direction of the width of the manuscript to change the standard position of placement of the manuscript relative to the image-forming portion and thus the paper. This achieves regulation of the optical axis between the manuscript and the paper.
However, in the case of the paper-supplying device provided with a plurality of paper-supplying portions adapted to be charged with paper-housing vessels in the directions of the rotary axes of shafts of the rollers, centers in the direction of width of the papers are inevitably shifted in position in every paper-housing vessel charged into the respective paper-supplying portions due to the slight shift in position between each paper-supplying portion and each paper-housing vessel, differences in the length of the paper-supplying course and the paper-supplying mode or errors in assembly of the device. Thereby, the regulation of the optical axes of the papers within the paper-housing vessels charged into a plurality of paper-supplying portions has been impossible by means of the above described manuscript-placing position regulating means.
In addition, paper-supplying roller shaft of the paper-supplying device adapted to be charged with the paper-housing vessel in the direction of the rotary axis of the shaft of the paper-supplying roller is provided with at least one paper-supplying roller, and the shaft provided with the roller removed from the body of the paper-supplying device when a worn paper-supplying roller is exchanged and other maintenance are conducted.
In order to take the paper-supplying roller shaft out of the body of the paper-supplying device, the connection of the paper-supplying roller shaft with the driving means is cancelled and a ball bearing supporting the paper-supplying roller shaft is removed. However, such operation of removing the paper-supplying roller shaft is remarkably difficult and troublesome and also a subsequent assembly operation likewise is difficult.
The present applicant has proposed a device, as shown in FIG. 15, in which a paper-supplying roller shaft 82 provided with a paper-supplying roller 81 is divided in the vicinity of both sides of roller 81, divided roller shafts 82a, 82b being overlapped one upon another at axial ends thereof, and the divided roller shafts 82a, 82b being connected with each other by means of screws 83 at such overlapped portions. Thereby, the divided shafts 82a, 82b provided with the roller 81 easily can be installed and detached by the simple operation of merely setting or removing screws 83. This arrangement is disclosed in Japanese Utility Model Application Laid-Open No. Sho 63-90646.
However, this device still has need for improvement in that in order to prevent roller 81 from being rotated and swung, a highly accurate processing technique for coinciding the axes of shafts 82a and 82b is required, and the cost is increased due to an increase in the number of parts.